This invention relates to an apparatus and a method for temporarily compacting multiply bent or convoluted, generally large pieces of sheet metal scrap resulting from manufacturing processes, such as sheet metal drawing procedures or sheet metal stamping processes and the like, which generate large quantities of irregularly shaped scrap pieces. Such scrap metal can be recycled by melting the scrap within conventional melt furnaces.
Typical scrap, ferrous metal trimmings from metal drawing or punching or stamping or the like processes, are multiply bent or convoluted, are irregular in shape, and are generally of substantial size. An example of such scrap pieces is the trimmings from edges of large sheets of steel whose center portions are deep drawn to form large sections of automotive vehicle bodies. Conventionally, the loose scrap metal pieces are piled into a container for transporting the scrap pieces to a place where the pieces may be stored and, ultimately, re-melted for recycling. The collected pieces, because of their convoluted or multiply bent, irregular shapes, occupy considerable volume. Thus, there is a substantial cost involved in transporting the large volume of collected pieces.
In order to reduce the volume of such collected pieces of scrap, attempts have been made to flatten their multiple bends and to compact the scrap pieces together by use of equipment which compresses the pieces together into large bales or blocks. Although this compression reduces the problems of transporting the otherwise larger volume of loose pieces, other problems result from that compression when melting the scrap. When such large bales or blocks, which can be a number of cubic feet in size, are put into a melt furnace, the length of time required for melting, and the amount of heat energy needed for melting, the compacted, dense bales or blocks, is substantially greater than that required for melting loose pieces of scrap. In general, loose pieces expose far more surface areas than a compacted block. Thus, the loose pieces of scrap are better and more quickly exposed to the heat of the furnace and to the pool of molten metal in the furnace. That results in quicker melting of the pieces. Also, conventional compression or baling equipment is relatively slow in operation and is large and expensive.
Prior attempts to reduce the volume of the scrap during transportation, and simultaneously to replace both conventional baling and transporting loose pieces of irregular, convoluted, scrap sheet metal pieces, involved flattening convoluted or multiply-bent pieces between heavy rollers. These loose, flattened pieces occupy much less volume than a random mixture of loose multiply-bent or convoluted pieces which are produced in manufacturing processes.
Another way of reducing the bulk volume of sheet metal pieces of scrap has been to utilize ram type equipment which compresses quantities of loose, multiply bent, scrap pieces directly into containers. An example of equipment which compresses scrap pieces into containers in which the compressed scrap pieces are transported, is disclosed in U.S. Pat. No. 6,418,841, issued Jul. 16, 2002, for a “System and Method for Compacting and Transporting Scrap Metal” invented by Jonathan A. Little and Donald R. Schomisch.
It would be desirable to have equipment and a method for continuously processing large, irregular, loose pieces of scrap metal to meet “mill ready” specifications (i.e. ready for melting), which eliminates some of the costly transportation and processing expenses and which would also improve the efficiency and speed of processing substantial quantities of scrap material that are continuously generated in large volume manufacturing processes.
Compacting loose pieces together into a bale or block reduces the bulk volume of the material, which reduces the expenses for transportation and storage of the scrap material. But, as set forth above, the trade-off is that such compacting increases the cost of melting the material as compared to melting loose, separate pieces. Hence, it is desirable to melt loose pieces which have more exposed surface areas as contrasted with the less exposed surface areas of compacted bales or blocks. That is, because the surface areas of the separated pieces of scrap metal are directly exposed to the heat so that they melt faster in a conventional electric arc melt furnace than when compacted into blocks which directly expose only much smaller outer surface areas to the heat.
The present invention is concerned with providing a method and apparatus which can continuously receive large quantities of irregularly shaped and multiply bent sheet metal pieces, and rapidly compress these pieces together into temporary, loosely or moderately compacted wafers or biscuits or slabs. These temporary wafers can be rapidly disassembled, after transporting them, into their constituent separate pieces when fed into a melt furnace.
The apparatus includes a ram-type press which compacts successive batches of individual, i.e. loose, sheet metal scrap pieces into layers which, in turn, are assembled together into thicker wafers or slabs. These wafers are sometimes referred to as biscuits. The individual layers and their respective pieces are temporarily held together by interlocked portions of their peripheral edges and by the interlocking of their adjacent, contacting, bent portions. The wafers, which are formed by a number of overlapped layers, can be disassembled, for example, by suspending the wafers horizontally and shaking or vibrating them so that the weight of their layers cause the layers and their constituent loosely or moderately compacted scrap pieces to pull apart and to fall down under the influence of gravity. Hence, the scrap pieces can be transported as unitary compacted groups which substantially reduce the volume during transportation, yet the pieces can later be fed into a furnace as separated loose pieces. The disassembly can be accomplished directly above a melt furnace so that separated pieces are fed into the furnace.